1. Field of the Invention
This invention relates to pumps, and, more particularly, to variable output pumps.
2. Description of the Prior Art
U.S. Pat. No. 713,817 discloses a windmill with control apparatus for varying the pumping of the windmill in response to changes in the velocity of the wind. A crank pin moves in response to the available wind energy to increase or decrease the length of the pumping stroke.
U.S. Pat. No. 733,799 discloses windmill apparatus in which the length of a pumping stroke is controlled in response to the discharge from the pump. The discharge from the pump is in response to need for water, as opposed to available wind energy.
U.S. Pat. No. 1,976,241 discloses a slot arrangement for a walking beam pump in which the crank pin radius is changed for changing the stroke of the pump. The crank pin radius is changed by physically altering the length of the crank arm through a pin arrangement.
U.S. Pat. No. 2,576,765 discloses another type of apparatus for changing the crank arm distance to vary the stroke of a pump through the use of a disc which includes a plurality of pin locations. The disc has an eccentric center of rotation, and thus varying the connection to adjacent elements by rotating the disc causes the length of the crank arm to vary.
U.S. Pat. No. 3,359,825 discloses an electric system for shifting a crank pin inwardly and outwardly through actuation of a gearing system.
It will be noted that none of the above-discussed patents utilizes solar energy or changes a pump stroke in response to changes of solar energy. The closest concept to varying the output of a pump in response to changes in output of solar energy is in the '817 patent, which changes the length of a pumping stroke in response to changes in wind velocity. As far as it is known, there is no apparatus which varies the stroke of a pump in response to solar energy changes, as does the apparatus of the present invention.
The apparatus of the present invention is designed to utilize solAr energy to pump water, as for livestock in remote areas, etc., where the apparatus will be substantially self-regulating and will be left unattended for substantial periods of time. Obviously, in such remote areas, the availability of electrical power is virtually nil. The use of gasoline powered or diesel powered engines is feasible, but such engines usually require an attendant for starting and stopping the engines, or at least to start them. Under some circumstances, a timer may be used to turn them off. With the apparatus of the present invention, a pump is actuated in response to solar energy, and the output of the pump is directly related to, or is in response to, the solar energy available.
While there are pumps on the market today which are operated by photovoltaic energy, most of the pumps are designed for shallowwell pumping. In most cases, the pumps are classified as centrifugal pumps, as opposed to positive displacement pumps.
For high-head, low flow pumping situations, a reciprocating volumetric piston pump, or pump jack, is preferred. This type of pump is, and has been, the standard of the oil industry since deep well oil pumping began, and it is also the standard for high head, low flow water pumping. However, such pump jacks have not been used more widely with photovoltaic power because of the typically gross mismatch between the electrical load requirements of the pumps and the output of photovoltaic (pv) arrays.
The apparatus of the present invention overcomes the problems of photovoltaic powered reciprocating piston pumps by providing a pump having substantially constant speed and continuously variable stroke responsive to the output of the pv array and a pump having variable speed and fixed, but selectively adjustable, stroke, with the speed responsive to the output of the pv array.